1. Field
The inventive concept relates to a base station signal matching device, and more particularly, to a base station signal matching device for matching a base station signal transmitted from a base station to be suitable for a distributed antenna system.
2. Description of Related Art
A distributed antenna system is an example of a relay system for relaying communication between base station and user terminals. The distributed antenna system is used in terms of service coverage extension of base station so as to provide mobile communication services to even shaded areas necessarily generated indoors or outdoors.
The distributed antenna system, based on a downlink path, receives a base station signal transmitted from a base station to perform signal processing, such as amplification, on the base station signal, and then transmits the signal-processed base station signal to a user terminal in a service area. Also, the distributed antenna system, based on an uplink path, performs signal processing, such as amplification, on a terminal signal transmitted from the user terminal and then transmits the signal-processed terminal signal to the base station. The matching of signals transmitted/received between base stations and the distributed antenna system is essential to implement such a relay function. Conventionally, external base station signal matching devices were used.
A conventional external base station signal matching device includes passive elements including an attenuator for adjusting the power of a base station signal to convert the base station signal having a high power level into an appropriate power level required in the distributed antenna system, a filter for dividing a duplexer type base station signal transmitted from a base station into a downlink and an uplink, and the like. The passive elements are very high-priced, and have large sizes. Therefore, it is difficult to miniaturize the passive elements.
Also, the attenuator is used in the conventional external base station matching device is a high-power attenuator capable of adjusting high power of base stations, but passive intermodulation characteristics of the attenuator are not satisfactory. Therefore, when a high-power base station signal is input to the distributed antenna system via the high-power attenuator on a downlink path, a passive intermodulation distortion (PIMD) signal is generated, and a spurious signal is caused as the generated PIMD signal is input through an uplink path. In addition, a large amount of heat is generated in attenuation of the high-power attenuator. Therefore, the base station signal matching device is damaged, and the lifespan of the base station signal matching device is shortened.